1. Field
The present invention relates generally to wireless communication, and more specifically to improved communication of higher priority information within a digital message.
2. Background
Wireless communication systems are widely deployed to provide various types of communication such as voice and data. These systems may be based on code division multiple access (CDMA), time division multiple access (TDMA), or some other modulation techniques. A CDMA system provides certain advantages over other types of systems, including increased system capacity.
A CDMA system may be designed to support one or more CDMA standards such as (1) the “TIA/EIA-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (the IS-95 standard), (2) the standard offered by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), (3) the standard offered by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in a set of documents including “C.S0002-A Physical Layer Standard for cdma2000 Spread Spectrum Systems,” the “C.S0005-A Upper Layer (Layer 3) Signaling Standard for cdma2000 Spread Spectrum Systems,” and the “C.S0024 cdma2000 High Rate Packet Data Air Interface Specification” (the cdma2000 standard), (4) the “TIA/EIA-IS-856 CDMA2000 High Rate Packet Data Air Interface Specification” (the IS-856 standard), and (5) some other standards. Non-CDMA systems include AMPS, GSM, and other TDMA systems. These and other wireless communication standards support voice and/or data communication at various data rates.
In the field of digital communications, various message formats are used for transmitting combinations of different types of data. In existing code division multiple access (CDMA) systems, for example, blocks of data, also known as “traffic,” are arranged into data frames containing various combinations of primary traffic, secondary traffic, and signaling traffic. Data frames containing either primary traffic and secondary traffic or primary traffic and signaling traffic are called “dim and burst” frames. Data frames containing either exclusively secondary traffic or exclusively signaling traffic are referred to as “blank and burst” frames. An exemplary set of frame formats for transmitting various combinations of dim and burst or blank and burst frames can be obtained from “TIA/EIA/IS-2000.3-A-1 Medium Access Control (MAC) Standard for cdma2000 Spread Spectrum Systems, Addendum 1,” hereinafter referred to as “1×.”
Each data frame is transmitted through a wireless channel between a base station and a remote station. Noise in the wireless channel can cause some transmitted frames to be received with bit errors. Such bit errors can then preclude proper decoding of the data frames at the receiver and cause loss of entire data frames. For some types of data, such as voice data, the loss of a frame does not require retransmission of the data in the frame. For other types of data, signaling data, for example, the loss of a frame containing such data requires retransmission of the data in a subsequent frame. Such retransmissions consume bandwidth that would be otherwise available for transmission of additional user data. Such retransmissions also cause delay in the ultimate reception of the retransmitted data, which can be detrimental when timeliness of signaling data affects the quality of the communication channel.
Thus, certain segments of a frame may be higher priority than other segments. However, an error in a lower priority section may require retransmission of the entire frame, even though the higher priority information was received correctly. There is therefore a need in the art for reliable transmission of higher priority data within a frame to reduce the delay and loss of bandwidth associated with errors in the frame.